drm/vc4: Add the DRM_IOCTL_VC4_GEM_MADVISE ioctl

This ioctl will allow us to purge inactive userspace buffers when the
system is running out of contiguous memory.

For now, the purge logic is rather dumb in that it does not try to
release only the amount of BO needed to meet the last CMA alloc request
but instead purges all objects placed in the purgeable pool as soon as
we experience a CMA allocation failure.

Note that the in-kernel BO cache is always purged before the purgeable
cache because those objects are known to be unused while objects marked
as purgeable by a userspace application/library might have to be
restored when they are marked back as unpurgeable, which can be
expensive.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20171019125748.3152-1-boris.brezillon@free-electrons.com

1 files changed, 30 insertions, 0 deletions

diff --git a/drivers/gpu/drm/vc4/vc4_drv.h b/drivers/gpu/drm/vc4/vc4_drv.h
index 87f2d8e5c134..9c0d380c96f2 100644
--- a/drivers/gpu/drm/vc4/vc4_drv.h
+++ b/drivers/gpu/drm/vc4/vc4_drv.h
@@ -74,6 +74,19 @@ struct vc4_dev {
 	/* Protects bo_cache and bo_labels. */
 	struct mutex bo_lock;
 
+	/* Purgeable BO pool. All BOs in this pool can have their memory
+	 * reclaimed if the driver is unable to allocate new BOs. We also
+	 * keep stats related to the purge mechanism here.
+	 */
+	struct {
+		struct list_head list;
+		unsigned int num;
+		size_t size;
+		unsigned int purged_num;
+		size_t purged_size;
+		struct mutex lock;
+	} purgeable;
+
 	uint64_t dma_fence_context;
 
 	/* Sequence number for the last job queued in bin_job_list.
@@ -192,6 +205,16 @@ struct vc4_bo {
 	 * for user-allocated labels.
 	 */
 	int label;
+
+	/* Count the number of active users. This is needed to determine
+	 * whether we can move the BO to the purgeable list or not (when the BO
+	 * is used by the GPU or the display engine we can't purge it).
+	 */
+	refcount_t usecnt;
+
+	/* Store purgeable/purged state here */
+	u32 madv;
+	struct mutex madv_lock;
 };
 
 static inline struct vc4_bo *
@@ -503,6 +526,7 @@ int vc4_get_hang_state_ioctl(struct drm_device *dev, void *data,
 			     struct drm_file *file_priv);
 int vc4_label_bo_ioctl(struct drm_device *dev, void *data,
 		       struct drm_file *file_priv);
+int vc4_fault(struct vm_fault *vmf);
 int vc4_mmap(struct file *filp, struct vm_area_struct *vma);
 struct reservation_object *vc4_prime_res_obj(struct drm_gem_object *obj);
 int vc4_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma);
@@ -513,6 +537,10 @@ void *vc4_prime_vmap(struct drm_gem_object *obj);
 int vc4_bo_cache_init(struct drm_device *dev);
 void vc4_bo_cache_destroy(struct drm_device *dev);
 int vc4_bo_stats_debugfs(struct seq_file *m, void *arg);
+int vc4_bo_inc_usecnt(struct vc4_bo *bo);
+void vc4_bo_dec_usecnt(struct vc4_bo *bo);
+void vc4_bo_add_to_purgeable_pool(struct vc4_bo *bo);
+void vc4_bo_remove_from_purgeable_pool(struct vc4_bo *bo);
 
 /* vc4_crtc.c */
 extern struct platform_driver vc4_crtc_driver;
@@ -557,6 +585,8 @@ void vc4_job_handle_completed(struct vc4_dev *vc4);
 int vc4_queue_seqno_cb(struct drm_device *dev,
 		       struct vc4_seqno_cb *cb, uint64_t seqno,
 		       void (*func)(struct vc4_seqno_cb *cb));
+int vc4_gem_madvise_ioctl(struct drm_device *dev, void *data,
+			  struct drm_file *file_priv);
 
 /* vc4_hdmi.c */
 extern struct platform_driver vc4_hdmi_driver;